Dehydrated lignite



Patented 0a; 6, 1925'.

EUGENE P. SO'HOCH, 01 AUSTIN, TEXAS.

DEHYDRATED LIGNITE.

Ilo mawm f ori mai applicati p flled July 17, 1922, Serial mi. 575,656. Divided and this application filed. Bugust 1a, 1924. Serial No. 732,751.

.To all whom it may concern:

Be it known that I, EUGENE P. Salmon, a citizen of the United States, residin at Austin, in the county of Travis and S iate of Texas, have invented certain new and useful Improvements in Dehydrated Lignite and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

dust or fine particles.

This invention relates to a dehydrated lump lignite fuel, and has for its object to provide a product which will be comparatively inexpensive to produce, and more efficientin use than-those heretofore proposed.

With these and other objects in view, the invention consists in the novel dehydrated lump lignite fuel constituting the *product, all as will be more fully hereinafter disclosed and particularly pointed out in the claims.

'This application is a division of my copending application Serial -Number 57 5.656 filed July 17, 1922 for dehydrated lignite and process of producing the same and now Patent No. 1,508,617, dated Sept. 16, 1924..

In order. that the precise invention may be the more clearly understood, it is said:

Fresh lignite as obtained in the mines contains say from 25% to 35% of moisture, which it looses when heated at 110 C. to constant. weight. Heated above this temperature, to 300 C. it gives up still more moisture, and some carbon dioxide; and heated still higher it begins to yield tar, and combustible gases; the deep-seated decomposition which it then undergoes involves an exothermic reaction so that the heating power ofthe products when used as a fuel is less than't-hat of the original material and the decomposition thus entails an actual loss of heating power.

When exposed to the air, raw llgnite gives up. alarge fraction of its moisture and disintegrates so extensively as to become mostly This same disinteation takes place in thefire when lignite is used as a fuel, and hence, unless special grates are provided, much of the lignite drops unburned into the ash pit. When heated in retorts or dryers to ex e1 the moisture, lignite disintegrates entire y, produeing dust or very sm l fragments.

7 amount of powder or small fragments.

The large amount of water in lignite and the fact that it disintegrates whenever it loses its water either in storage or during combustion, naturally affects its commercial value greatly, and hence improved processes for making a better form of fuel out of lignite have been and are being actively sought. The only process heretofore known to me or proposed, for producing a better form of lump fuel from lignite consists of retorting the material and briquetting the resulting powder. This requires 10% or more of a first class asphalt, coal tar pitch or other suitable carbonaceous binder, a mixing operation to impregnate the powder with the binder.. and then briquetting the material with strong presses. The difficulty of doing this economically and the high cost of the initial installation has retarded capitalists from entering into th1s business. It results that the proper machinery, aswell as the details of the whole process are today still in their experimental stages. Y

I have discovered, on the other hand, that when fresh lump lignite is heated in a still and immersed in thin petroleum oil, such as gas oil orengine distillate, it gives up its moisture without forming any appreciable In fact, the'original lumps'remain intact, al-

-though they may have formed some cracks.

Most of these cracks are very fine, while large parts of the pieces are entirely free from cracks.-

In carrying out this process. I therefore prefer to cover the'lignite entirely with oil and to use the lumps as they ordinarily come from the mine, when they range, say, in smallest dimensions from 1 inch to 5 inches, and in largest dimensions from 3 to 8 inches. The time required to raise the temperature of the mixture to 250 C. in the still is about two hours. At the end of that time, no moisture appears to be coming from the still. The oil is then drained out of the still. An examination of this oil-heated ite shows that all the lumps retain their onginal form, and although the treated material is brittle, yet most of the pieces are sufliciently firm to be handled without disintegration. As compared with some of the same lignite which is air-dried simultaneously, the oil-dried lignite shows a much smaller number of cracks,

which do not gape open as wide as is the.

to 300 C. for about two hours. The oil is then drained out of the still while it is hot. When this last named procedure is completed, it is found that the lumps have retained so little of this thick oil on the outside as to leave them practically dry, although the material has been so thoroughly permeated with the oil as to be non-brittle, and hence capable of standing a good deal of handling withoutextensive breaking of the lumps. In fact,

it is found that, at most, only the lumps with diameters. larger than 3 to 4.- inches may break up and that none of the fragments formed are smaller-than a pecan'nut, while most of them range in size from a hens egg upward. I prefer to use a thin oil in-the first treatment because a thick oil foams when steam is formed in it at or near the boiling point of water, and it probably does not soak into the cracks as readily at a relatively low temperature as a thin oil does.

Upon examination, the final product produced by the two treatments above described gives the following results:

Volatile combustible matter, 51.13% fixed carbon, 39.42%; ash, 9.45%; heating power, 13032 B. t. u.; moisture, none. T

The same raw untreated lignite gives the following results:

Moisture, 28.15%; volatile combustible matter, 32.07%; fixed carbon, 31.59%; ash,

8.19; heating power, 8641 B.-t. u. V

Assuming that 10% of oil was retained. by the treatedlignite and that the oil has a heating power of 19250 B. t. u. per und p0 "cold, but thin when hot.

we obtain the following figures by calculation: 9

Heat obtained from the 10% oil in 1 lb. of material, 1925 B. t. u.: heat obtained from the lignite in 1 lb. of material, 1110'? B. t. u.; heating power of of this lignite without oil. 12340 B..t. u.; perbent loss of moisture and other non-combustible volatiles from original lignite required to raise its heating power from 8640 B. t. u. to 12340 B. t. u., 30%.; per cent of remaining volatile combustible matter in raw lignite, 30.22%. It shouldbe noticed that in the above operation the lignite was heated much above C. and theta part of the 32.07% -volatile combustible matter of'the raw lignite was also expelled. That is, we should take from the above 30% loss of moisture and other non-combustibles the moisture content of 28.15% of the raw lignite to get the difference amounting to 1.85% and this difference of 1.85% should be subtracted from the 32.07 in the raw lignite, thus. leaving the 30.22% of remaining volatile combustible matter arrived at before.

The latter per cent of volatile combustible matter (30.22) together with that of fixed carbon (31.59) and ash (8.19) in the raw. lignite will be larger inthetreated lignite by the amount corresponding to the loss of 30.0% volatiles lost minus.10-% of oil added, or in other words, the per cents of those ingredients will be increased in the ratio. of 70 to 90, and hence become, volatile combustible matter plus 10% oil, 48.90% fixed carbon, 40.60% ;v ash, 10.50%.

These figures are found to be in part greater and in part smaller than those obtained by examining the treated lignite. Hence, we may consider that 10% to 20% of oil is approximately the amount absorbed. Since the material was allowed, toabsorb and retain all of the oil that it would, we may further look upon the amount/of 20% to be the maximum it can take up. This is of importance in comparin the cost! of this process now proposed or the conversion of lignite to an industrially suitable form, namely that of retorting and briquetting. In the latter process, the lignite 1s retorted to an extent that removes all the moisture plus some combustible gas and tar, and in this 0 eration the lignite disintegrates practica ly entirely into a powder or granular mass. This mass must then be mixed with a suitable binder and pressed.

with powerful presses, into briquettes of ,various suitable shapes.

,Many binders have been proposed for this pur ose, but at present on] two kinds seem to g suitable (a) a the]; asphaltic or pitchy "residues left and obtained in the distillat1on of coal tar or of crude petroleum.

These residues must be made up of compounds which are stifl' and tough' when (b) starchy or syrup llke resldues suchv as are obtained in making sugar, (e. g., black strap molasses), and from. paper manufacturing (sulphite pitch). These binders are soluble .in water and hence are less suitable than the class (a) binders.

The better class of'bindersthose' of class (a) must be used in a minimum amount'of 10%. Even this amount will not-coat every speck of the lignite powder so thoroughly as. to prevent the absorptionof moisture,

the asphalt or-pitch must be as to give the briquettes" I the roper rigi 'ty.

Furthermore of high grade, that is, it must become so stifi on coolin I eseextreme and costly requirements, on the other hand, do not need to be met by the thick oil I use to impregnate the lumps of oil-heated lignite. This thick oil serves to make the mass elastic, and while it glues together some of the split-planes, yet the rigidity is maintained b inherent hardness of most of the materia and not by the binder. It is surprising that only 10% to 20% o f oil is absorbed by this lump .lignite, even though no attempt is made to press the cracks, etc., close together. But a probable explanation resides in the fact that none of the tar or oily components of the original lignite are destroyed by my oil-heating process, while any process of retorting lignite certainly destroys from 5% to 10% of these components present.- My procedure, accordingly, takes advantage of this important fact. I

In order to reducethe volatility or flashing of my product to a minimum I remove the lighter oils from the thick oil by bubbling steam through it while the lignite is heated with it. The resulting oil will naturally glue up the cracks somewhat firmer than a thinner oil, yet this is not essential to make the material retain its shape while it is handled. The steaming out of the light oil is done only to remove some of the most volatile oil.

From the foregoing, it will now be clear that my process provides a procedure which is comparatively inexpensive and simple to carry out, while it also produces fuel lignite of a high calorific value in its natural lump form capable of being handled without briquetting. Further, it is found that this oil treated dehydrated lump lignite is not materially affected by repeated wetting and drying in the hot sun. It does not soften in the flame and the lumps do not crack to an objectionable extent while burning, but retain their form until burned to ash. In other words, the finished product simulates the behavior of bituminous coal on burning, except it does not melt and fuse together."

An important feature of the invention resides in the fact that it requires only rela tively cheap oils which are plentiful instead of equal amounts of the expensive asphalts now used in briquettin The bearmg of this upon our large on eveloped lignite deposits needs no comment.

The finished product is preferably produced in the lump form above mentioned, but of course it could be as readily produced in a finer or a coarser form, or it could be used as a raw material like finely divided coal for making briquettes, or it could even be mixed with coal. When in the lump form.

smooth surfaces. After the treatment with a heavy crude oil the toughness is increased and the lumps take on the dark shiny appearance of soft coal. In bothcases the product can b readily distinguished from the raw lignite both by its physical appearance and by its'toughnessr It is obvious that those skilled in the art may vary the details of the procedure, as well as the form of the finished product without departing from the spirit of the invention, and therefore I do not wish to be limited to the above disclosure except as may be required by the claims.

What is claimed is:

1. The herein described new article of manufacture comprising lumps of raw dehydrated'lignite impregnated with a hydrocarbon oil, substantially as described.

2. The herein described new article of manufacture comprising raw dehydrated lump ligniteimpregnated with a substantial percentage by weight of a hydrocarbon oil, substantially as described.

3. The herein described new article of manufacture comprising lump lignite of the general shape it comes from'the mine and impregnated with a hydrocarbon oil, substantially as described. I

4. The herein described new article of manufacture comprising dehydrated lump lignite of the general shape it comes from the mine impregnated with a substantial percentage by weight of a hydrocarbon oil, substantially as described.

' 5. The herein described new article of manufacture, the same consisting of raw dehydrated l'umps of lignite partially impregnated with an oil, said lumps being of a suflicient toughness to be handled without becoming finely subdivided, and capable of being burned while retaining their shapes. substantially as described.

6. The herein described new article of manufacture, the same consisting of dehydrated lump lignite impregnated with an oil and having a cohesive strength substantially as great as that of the raw lignite, from which it was derived, substantially as described.

In testimony whereof I afiix my signature.

EUGENE P. SOHOCH. 

